#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
#define MOD 1000000007
#define endl '\n'
#define pb(v,i) (v).push_back(i)
#define vll vector<ll>
#define pll pair<ll,ll>
vector<pll> edges[200005];
ll edgedepth[200005], weightdepth[200005];
ll root, seconddaddy[200005];
int K;
vll visited;
void dfs(ll node, ll par){
if (node == par) seconddaddy[node] = node;
else if (par == root) seconddaddy[node] = node;
else seconddaddy[node] = seconddaddy[par];
if (weightdepth[node] > K) return;
pb(visited, node);
for (auto [nd, w] : edges[node]){
if (nd == par) continue;
edgedepth[nd] = edgedepth[node] + 1;
weightdepth[nd] = weightdepth[node] + w;
dfs(nd, node);
}
}
int best_path(int N, int k, int H[][2], int L[]){
K=k;
int ans = 5*N;
for (int i=0; i<N-1; i++){
edges[H[i][0]].push_back({H[i][1], L[i]});
edges[H[i][1]].push_back({H[i][0], L[i]});
}
for(root=0; root < N; root++){
memset(edgedepth,0,sizeof(edgedepth));
memset(weightdepth,0,sizeof(weightdepth));
memset(seconddaddy,0,sizeof(seconddaddy));
dfs(root, root);
for (int ni=0; ni < visited.size(); ni++){
for (int nj=ni+1; nj < visited.size(); nj++){
ll i = visited[ni], j = visited[nj];
if (seconddaddy[i] == seconddaddy[j] or weightdepth[i] + weightdepth[j] != K) continue;
ans=min(ll(ans), edgedepth[i] + edgedepth[j]);
}
}
}
return (ans == 5*N ? -1 : ans);
}
